In fourth place, with 1,627 votes, an inquiry into the tenuous nature of U.S.-Arab relations: Why do people in Arab countries insist on touching my beard, then taking the same hand and kissing their fingers in a sort of "Italian, it's delicious!" gesture?

In third place, with 2,107 votes, a question worth asking in the aftermath of the Christmas Day bombing: Are there really badass muthas like 24's Jack Bauer working for the U.S. government?

In second place, with 3,240 votes, a query that doesn't have much to do with anything: Why do auctioneers talk like that?

And finally, with 6,028 votes, the winner by a landslide and our official Explainer Question of the Year for 2009:

How would the law punish Siamese twins if one of the twins committed murder without the other being involved?

The answer: No one knows.

Advertisement

There isn't much case law to work with on this question, since in the United States, at least, conjoined twins represent something like 0.0005 percent of all live births—with an even smaller number surviving into adulthood. The conjoined twins who aren't separated at birth and do manage to grow up have so far tended to be more or less exemplary citizens.

That said, there have been a few recorded instances of conjoined criminality. By one account, the original Siamese twins, Chang and Eng Bunker, were arrested over a scuffle with a doctor who tried to examine them, but never prosecuted. Nor were they ever charged with bigamy, despite having taken two wives.

A more recent case concerned the Filipino twins Lucio and Simplicio Godina, who as children were rescued from a Brooklyn, N.Y., sideshow, and later toured the United States as the "only pair of male Siamese twins on Earth." In March 1925, newspapers claimed that Lucio had learned how to drive a car and been arrested after his vehicle grazed a carabao cart on a street in Manila. Simplicio supposedly appealed the case on the grounds that as an innocent man, he could not legally be incarcerated—and the judge let both twins go free. A similar story was reported in the New York Times in 1929: This time, Lucio was able to escape punishment for making an improper left turn in downtown Los Angeles.

These stories—true or not—reveal how difficult it would be to punish a conjoined criminal with an innocent twin. Let's say you wanted to throw the evil sibling in jail. There's no way to do that without incarcerating the good one as well (unless you convinced him to take a job as a prison guard). Is there any way around this problem?

The best analogy might be a pregnant convict, who, like our conjoined criminal, is physically attached to an otherwise innocent member of her immediate family. When you throw a pregnant woman in jail, you're locking up her fetus, too. (Indeed, something like 10,000 pregnant women are now in federal or state prisons.) At first glance, incarceration means little to a developing fetus, though, whereas an innocent, adult twin would suffer for it. On the other hand, there's some evidence that expectant mothers often receive inadequate prenatal care in prison. When an inmate finally gives birth, the baby is either taken away from her—which could be seen as its own form of punishment for the newborn—or it remains with the mother for up to a year in a prison nursery. Either way, the baby might be harmed by the incarceration of the mom.

It's not unusual for the courts to take such collateral damage into account when sentencing a defendant. A new book by the legal scholars Dan Markel, Jennifer M. Collins, and Ethan J. Leib looks at how "family ties" are (and should be) handled in the criminal-justice system. One part of their analysis concerns the practice of offering lesser punishments to those defendants who serve as caregivers for their families. Let's say you throw a criminal in jail and as a result, his innocent and sickly grandmother suffers without anyone to provide for her. In that case, you might be tempted to shorten the prison term or substitute home detention or supervised release. In fact, some state legislatures have expressly permitted these sorts of arrangements. (A recent study of criminal cases in Pennsylvania found that judges make a habit of going easy on caregivers.)

By that logic, a judge might give a break to a conjoined criminal so there would be less harm to an innocent member of his immediate family (this being the most literal of "family ties"). But the two situations aren't exactly analogous: It sometimes happens that innocent people are harmed as a result of a family member being thrown in jail, but that's different from the state taking deliberate action to punish someone for a crime he didn't commit. To toss someone in prison along with his evil twin seems more like the latter. So even if, say, the sentence for a conjoined murderer were discounted by half, the good twin would still receive an unwarranted punishment.

There are some other possible solutions to the problem, however. You might throw both twins in prison but treat only the guilty one as if he were a convict. When the siblings were released, for example, the good twin would have all the rights of a normal citizen, while the evil twin would have lost the right to vote, be registered as a sex offender, etc. You might even compensate the good twin according to the relevant payout rules for wrongful convictions. (Those who were wrongly incarcerated for a federal crime can get up to $50,000 per year, or $100,000 if they were on death row.)

Of course, jail isn't the only way to punish a criminal. In a thoughtful analysis of the conjoined-criminal problem, law student Nicholas Kam considers several other kinds of sanction. Capital punishment seems out of the question, since the good twin might be killed as well. (You can't execute a pregnant woman in the United States, either.) So long as the legislature permitted it, the courts might impose a fine on the guilty twin instead of a prison sentence. But as Kam points out, it's been a long, long time since monetary sanctions have been used to punish violent crimes. It's also hard to imagine that a fine wouldn't affect the innocent twin as well.

Another possibility would be enforced separation. There's little chance that the courts would allow for this kind of violation of the body, however. Even if they did, the logistics would be prohibitive. The appropriate surgery can be extraordinarily complicated—one recent case took 26 hours and a small army of surgeons—and it doesn't always work. Still, there's at least one precedent for this situation: In 2000, a British court ordered the surgical separation of a pair of conjoined twins, known as Mary and Jodie, against their parents' wishes. Doctors had testified that both would die if the operation were not performed. (It was, and Jodie survived.)

All of the above assumes that one twin is unambiguously guilty, and the other is unambiguously innocent. In real life, it's hard to imagine such a clear-cut case. For example, a jury might be inclined to believe that the "good" twin acted as an accomplice, or perhaps an accessory, to the crime after the fact. This charge would apply if one sibling knew that the other had committed a crime—which seems likely under any circumstances—and that he intentionally provided assistance or comfort to his sibling rather than calling the police at the first opportunity. If the good twin were convicted of an accessory crime in federal court, he'd be subject to at most half the prison term appropriate to his evil brother. In some states, however, it's legal to harbor a fugitive if that person happens to be your sibling.

One more way that a "good" twin might be convicted, even if he took no part in the actual committing of the crime: In some states, he might be found guilty of not stopping his brother. Although as a general rule, common-law tradition dictates that you can't be held accountable for something you didn't do, 10 states have so-called "duty to rescue" statutes. These require innocent bystanders to call the police or reasonably attempt to aid a victim in distress. (In four of these states, siblings of the offender are exempt from the law.) If one twin tried to stab someone, the other might be expected to grab his arm or drag both of them to the ground. The penalty for failing to rescue is usually a fine, though some jurisdictions allow for up to a year in prison.

Bonus Explainer: Could an innocent conjoined twin be compelled to testify against her evil sibling? Absolutely. In the United States, spouses tend to have special privileges when it comes to testifying against each other. A handful of states offer similar protections to parents who don't wish to testify against their children. But siblings—conjoined or not—have no such right.